Convection current responsive instrument



April 20, 1948. v. K. zwoRYKms 4%89 CONVECTIDN CURRENT RESPONSIVE INSTRUMENT Filed April 15, 1945 la @l-2225553 INVENTOR. 70 60A/7R01. CMCW/J VLADIMIR K. ZWORYKIN -wig fu :How/v k f/v ,las By Y 4free/wy Patented Apr. 2o, 194e 2,440,189 CONVECTION CURRENT RESPONSIVE RUmNT INST Vladimir K. Zworykin,k

to Radio Corporation of Delaware Princeton, N. J., assigner of America, a corporation Application April 13, 1945, Serial No. 588,233

The present invention relates to control and measuring devices and more particularly to an instrumentality wherein an unbalance between two normally balanced resistances develops a potential useful as a control or measure of a condition.

Some oi the objects of the present invention are: to provide a. novel apparatus wherein a heat convection current functions in association with an electrical agency for a useful purpose; to provide a unit, including two electrical conductors and a heating element, wherein variation of the impinging angle of the convection currents from the heating element upon one conductor causes a differential resistance between the conductors to actuate an indicator, a measuring instrument or a control mechanism; to provide a unit responsive to a change of position for stabilizing a body otherwise subject to the motion imparted to the unit; to provide a device including two electrical conductors so positioned and arranged with respect to a heating element as to have a selected ratio of resistance and functioning upon a change of position with respect to said heating element to vary the resistance ratio, such varied ratio being utilized to operate an assiatecl agency; to provide a device including two electrical conductors arranged in one position to be equally heated by a heating element and balanced as to resistance, and in a second position to be unequally heated and unbalanced as to resistance, whereby an associated agency is caused tc operate as a function of the diilerential resistance; and to provide other improvements as will hereinafter appear.

In the accompanying drawings, Fig. 1 represents one form of the present invention, the same being embodied in a tube lshown in elevation; Fig, 2 represents a section on line 2-2 of Fig. l; Fig. 3 is a diagram of a bridge circuit asv associated with the invention for response to a differential resistance caused by an angular impinging of a heat convection current upon one of two electrical conductors; Fig. 4 represents a Perspective of an apparatus illustrating one application of the invention; and Fig. 5 represents a transverse section of a tube showing a modified form of the invention for two dimensional operation.

Referring to the drawings, the present invention broadly comprehends mounting two electrical conductors Ill and lI in position to be heated Abv a heating element I2 preferably in the form of wire disposed between and spaced from the conductors I0 and II. These conductors are preferably composed of a metal having a high 10 Claims. (C1. 177-1351) temperature coefhcient of resistance in order that small temperature variations will be manifest by the change of resistance in the conductor. Since the device is arranged to function by reason of a change of the angular relation of a convection current from the element I2, the conductors l0 and I I and the element I2 are preferably mounted vertically parallel and in the same plane, the conductors being generally equidistant from the element I2. The element l2 is included in a circuit energized by a source of voltage i E.

One form of the invention mounts the con` ductors I0 and il andthe element l2 in a glass tube I4, preferably sealed and lled with an inert gas as the medium for circulating convection currents emanating from the heating element i2.V As long as the circulation is such as to maintain a balance of the resistances of the two conductors, no useful potential is created but when the angular relation of the convection current is altered to influence one conductor more than the other, then the relative temperature change of the conductors produces a differential resistance capable oi operating an electrical agent associated, therewith.

One mode of operating the invention is to mount the tube I4 to swing with a pendulum movement whereby the conductors lll and i I and the element i4, assume an angular position with respect to the vertical axis of the tube. As shown, the tube I4 is clamped or otherwise made fast to a base i5 carried by and keyed to a rock shaft I6 arranged to be oscillated by any suitable mechanical movement. With the base l5 stationary s0 that the tube M and the contained conductors l0 and I I and the element i2 are Vertical, then the convection current from the heated element I2 will maintain both conductors at the same temperature so that the resistance thereof is balanced. If the base I5 is now swung counterclockwise, as seen in Fig. 4, the top of the tube will swing to the left and angularly dispose the conductor I I 'above the heating element l2 and the conductor I0 below the heating element I2. As a. result, the conductor I l is in the path of the rising convection current which implnges thereagainst at an angle so that the temperature of that conductor rises to thereby cause a change of resistance giving a differential which serves as a measure or control voltage. When the tube I4 is rocked to the right, a differential resistance is obtained in the same way by the impinging of e the convection current upon the conductor I0.

As a means of utilizing this change of resistance for a useful purpose, the two conductors lll and agentes ii form respectively two arms of a bridge circuit, shown in Fig. 3, wherein the other arms comprise two resistances i1 and i8 in series relation as a part of a variable resistance whereby the bridge is initially balanced with respect to the conductors in and Il. A source of voltage 20 serves to energize the bridge as will be understood and in the present instance is in the form of an A. C. generator. The bridge is preferably balanced with the tube I4 in a vertical position so that the resistance of the two control conductors I and i l is equal, though the invention is not limited to such vertical` position, as obviously an inclined position may be taken and a selected ratio of resistance become the zero or reference position. When the tube is moved, either as a swing or bodily laterally, one oi the conductors I0 or Il (according to the direction of motion) has its temperature raised so that the bridge becomes unbalanced. This unbalance creates a voltage in the output,

-which can be measured by a galvanometer or other indicating instrument, or can be used for control purposes by any suitable amplification.

As shown in Fig. 3, the output conductors 2i and` 22 are connected to the input of an amplifier 23 which ampliiies the differential' voltage as a control for a two-phase motor 24. One of the phases is applied from a source which may be the generator 20. The other phase is applied through I an amplifier 23. The amplifier 23 is preferably of the type shown in U. S. Patent No. 2,208,623, which has the necessary characteristics to minimize hunting.

Referring to Fig. 4, the motor 24 is shown mounted upon a platform 2B which is carried by journals 26 supported by standards 21 from a nxed base 28. The platform 25 receives an undesired oscillating movement from any suitable source and the function of the tube i4 is to prevent the platform oscillations from being reproduced in the base i5. Thus, the platform 25 may be a part of a ship or other vehicle or object subject to wave motion while the base l5 may be a gun or camera mount which is to be stabilized and to be made unresponsive to the oscillation. A box 30 forms a housing for a reduction gear whereby the speed of the motor shaft 3| i's reduced at the shaft i6. Applying the functioning of the bridge of Fig. 3 to the apparatus of Fig. 4, it will be seen that a swing of the platform 25 in one direction will be transmitted to the base i5 and thereby tilt the tube i4 so that one of the conductors ill or il will be heated more than the other thereby to unbalance the bridge, and cause a voltage to operate the motor 2li to turn the shaft i6 in a direction counter to the transmitted swing. When the platform 2 5 swings in the opposite direction the tube i@ again controls the motor 2d, this time to cause a reverse rotation again to nullify any movement to the base i5. rI'he control by the motor 2d, in response to the resistance differential of the conductors in the tube lil, is so sensitive that the shaft IS is held stationary and consequently while the platform 25 continues to oscillate, the base i5 is held fixed.

:in Fig. 5 of the drawings a transverse section of a modied form of the invention wherein a tube 32 is provided with two conductors 3d and tid in the same plane and two conductors @Ei and 3@ in the same plane but at right angles to the plane of the other two conductors. All of the four conductors are symmetrically disposed with respect to a centrally located heating element Bl.

circuits. as will be understood. The tube 32 is arranged for mounting on a suitable tiltable unit to function in the manner described for the form of the invention shown in Fig. 1.

The same device can be used for measuring the acceleration. It is due to the fact that when the tube is accelerated, the gas inside of the tube `has the tendency to preserve its initial position in space and, therefore, will be displaced in the respect of the filaments. Therefore, the filaments in the opposite side of the displacement will be heated more than the one on the same side. The actual measurements indicate that for certain range of acceleration the change in resistance is linear proportional to acceleration. Such 'a tube can be used as an indicator for measuring the acceleration or information from this tube can be applied to other devices to produce the controls as forms of acceleration.

I claim as my invention:

1. An apparatus of the character stated, comprising a heating element, means to heat said element, two temperature responsive electrical conductors equally spaced from said element and initially balanced as to resistance by equal convection currents from said element and responsive to changes of the implnging angle of said convection currents relative to said conductors to cause a differential resistance between said conductors, means to `mount -said element and said conductors in a vertical position, means to tilt said mounting means to cause unequal currents to'unbalance said conductors, and an electrical agency associated with said conductors and operable as a function of said differential resistance.

2. An apparatus of the character stated, comprising a heating wire mounted in stretched condition, means to heat said wire, two electrical conductors having the same resistance, means to mount said conductors parallel to said heating wire and equally spaced therefrom, means to move said wire and conductors while maintaining the spaced parallel relation to change the relative intensity of said convection currents from said wire to said conductors to minimize the dierential resistance between said conductors, and means responsive to said diierential resistance for indicating said relative intensity.

3. An apparatus of the character stated, comprising a heated wire vmounted in vertical stretched condition, means to heat said wire, two electrical conductors having the same resistance, means to mount said conductors parallelto said heating wire and equally spaced therefrom so that the wire convection current maintains a state of resistance balance between said conductors, means to swing said wire and conductors while maintaining the spaced parallel relation to change the impinging angle of said convection current to cause a diierential resistance between said conductors, means responsive to said dierential resistance for restoring a state of balance between said conductors.

Thus, a two dimensional control is possible by including the two pairs of conductors in bridge prising a tube,

convection current from differential ratio convection current 'from said wire to cause an unbalanceof said resistances, and means connected to said conductors to indicate the amount of said unbalance.

5. An apparatus of the character stated, coman inert gas sealed in said tube, a heating wire in said tube, two electrical conductors vhaving the same resistance in said tube, means to mount stretched parallel relation, equally spaced from said plane, means to heat said said tube to normally maintain' said wire and conductors vertical, means to swing said tube to bring one of said conductors in the path of the said wire to cause an unbalance ot said resistances, and means associated with said conductors and responsive to thediilerential resistance for restoring the balance between said conductors.

6.v An apparatus of the character stated, com` prising a tube, an inert gas sealed in said tube, a heating said conductors being wire and in the same ance ratio, means to mount said wire and conductors in stretched parallel relation, said conductors being equally spaced from said wire and in from its initial position to vary pinsing ansie of the convection current on said conductors, and

means responsive to the varied for restoring said tube to its initial position.

7. An apparatus of the character stated, comprisins a tube. an

inert gas sealed in said tube, a

' heating wire in said tube, means to heat said wire, two electrical conductors in said tube having a predetermined resistance ratio, means to mount said wire and conductors in stretched parallel relation, said spaced from said wire and in the same plane, a bridge circuit including said conductors. means to balance said circuit for zero voltage output, means to swing said tube from its initial position to vary said resistance ratio, due to a change in the impinging angle of the convection current on said conductors, and unbalance said bridge to produce a voltage output, and means including a reversible motor responsive to said voltage output to restore said tube to its initial position.

8. An apparatus of the character stated, comprising a heating element. means to heat said element, four temperature responsive electrical conductors equally spaced from said element and arranged in parallel pairs respectively in planes at right angles, said element being common to said wire and conductors in wire, means to mount wire in said tube. two electrical conduc-` tors in said tube having a predetermined resistconductors being equally Number Name v Date 1,335,055 Hedenstrom Mar. 30, 1920 1,351,356 'Iucker L Aug. 31, 1920 1 822,184 Wunsch Sept. 8, 1931 5,014,998 Baguby sept. 17, 1935 60 2,056,769 Buchting Oct, 6, 1936 A 2,237,077 Lanck Apr. 1, 1941 FOREIGN PATENTS Number Country Date 243,048 Great Britain Nov. 16, 1925 357,784 Germany Aug. 31, 1922 425,059

said planes, a tube enclosing said element and conductors, means to mount said tube to swing in either conductor plane to change the impinging angle of convection currents from said element to cause a dierential resistance between a corresponding pair of said conductors, and an electrical agency for each pair responsive to said diierential resistance and operable as a function of said resistance.

9. An apparatus of the character stated, comprising a tube, a heating wire in said tube, two electrical conductors having resistance in said tube, means to mount said Wire and conductors in substantially parallel relation, said conductors being spaced from said wire and in substantially the same piane, means to heat said wire, means to mount said tube to normally maintain said wire and conductors in a reference condition whereby movement of said tube causes an unbalance of said resistances, and means connected to said conductors to indicate the amount of said unbalance.

10. An apparatus of the character stated, comprising a tube, an inert gas sealed in said tube, a heating wire in said tube, a plurality of electrical conductors having the same resistance in said tube, means to mount said wire and conductors in' stretched parallel relation, said conductors be- "dicating the amount of said unbalance.

VLADIMIR K. ZWORYKIN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Germany Feb, 6, 1926 

